Image-processing device, image forming device, electronic equipment, and image forming method

ABSTRACT

An image forming apparatus includes an image forming system having a pickup roller ( 36   a ) that extracts and supplies a recording paper (P) housed in a paper cassette ( 33 ), a photosensitive drum ( 31   b ) that forms an image on the recording paper (P) supplied by the pickup roller ( 36   a ), and the like. In the case that multi-feeding has occurred in which when the pickup roller ( 36   a ) supplies a first recording paper (P 1 ) another recording paper (P 2 ) is also supplied, and the first recording paper (P 1 ) is between the photosensitive drum ( 31   b ) and the other recording paper (P 2 ), image forming processing for the first recording paper (P 1 ) by the image forming system is continued.

TECHNICAL FIELD

The present invention relates to an image processing apparatus, an imageforming apparatus, an electronic equipment, and an image forming method,provided with a function that detects multi-feeding in which paper suchas recording paper loaded on a placement stage is fed in a state withtwo or more pages stacked.

BACKGROUND ART

A scanner apparatus, copy apparatus, facsimile apparatus, or amultifunction machine in which any of these apparatuses are combined isprovided with an original reading apparatus for reading imageinformation of an original, and an image forming apparatus for forming atoner image on a photosensitive drum based on image information of theread original and transferring the toner image to recording paper.

In this case, in the image forming apparatus, when feeding recordingpaper page by page from a plurality of pages of recording paper thathave been placed on a placement stage and transporting the suppliedrecording paper to an image forming portion constituted from aphotosensitive drum or the like, two or more pages of recording papermay be supplied stacked together due to friction or the like betweenpages of recording paper piled on the placement stage. In this case,depending on the feed method and the feed structure (such as straightfeed or reverse feed), when image forming, an image is formed straddlingthe plurality of pages of recording paper that have been multi-fed, andso there was the problem that image defects and waste of recording paperoccurred.

Consequently, image forming apparatuses provided with a means forsolving such problems have been proposed in the conventional technology.

For example, image forming apparatuses have been proposed with aconfiguration in which duplex copy, simplex copy, and multiple copymodes are provided, in the simplex copy mode the copy operation iscontinued even if multi-feeding of recording paper is detected, and anotification is made of the page number when multi-feeding occurs (Forexample, see JP S61-113076A. Hereinafter, referred to as “PatentDocument 1”.).

Image forming apparatuses have also been proposed with the followingconfiguration. When recording paper has been multi-fed, only thetransport operation of that recording paper is permitted, the output ofimage data to the corresponding recording paper is prohibited, and whenthe next recording paper has been normally separated and transported,the recording paper transport operation and output of image data areallowed. By separating the multi-fed recording paper to a vacant tray asa blank page, defective printing is prevented and multi-fed recordingpaper is separated (For example, see JP H7-140854A. Hereinafter,referred to as “Patent Document 2”.).

Further, image forming apparatuses have also been proposed with aconfiguration in which, by printing to only the final recording paperwhen recording paper has been multi-fed, the waste of recording paperand printing time is reduced (For example, see JP H7-125351A.Hereinafter, referred to as “Patent Document 3”.).

With the technology disclosed in above Patent Document 1, when simplexprinting is performed, all printing is performed regardless of the stateof multi-feeding. However, when the feed mechanism is a top-intakereverse feed mechanism, for example, the recording paper that has beenmulti-fed becomes positioned between the image forming portion and therecording paper on which an image should be formed, and in this case theproblem occurs that printing is performed with the print image dividedonto a plurality of pages of recording paper. That is, in theconfiguration disclosed in Patent document 1, because the relationshipof the multi-feeding state with the structure of the mechanism of theimage forming portion and the feed method is not considered at all, thesort of problem described above occurs.

Also, with the technology disclosed in above Patent Document 2, aconfiguration is adopted in which, when recording paper has beenmulti-fed, only the transport operation of that recording paper ispermitted, and the output of image data to the recording paper isprohibited. However, there was the problem that the recording paper forwhich printing is not performed may be unusable, due to the occurrenceof affixing paper dust in the image forming portion by allowingrecording paper for which printing is not performed to pass the imageforming portion, affixing fixing oil by allowing the recording paper topass the fixing portion, curling due to heat, and the like.

Further, with the technology disclosed in above Patent Document 3, aconfiguration is adopted in which printing is performed on the finalrecording paper when recording paper has been multi-fed, but when thefeed mechanism is a top-intake straight feed mechanism, for example, theother multi-fed recording paper or the initial recording paper on whichan image should be formed become positioned on the recording face sideof the final recording paper, and so the problem occurs that likedescribed above, printing is performed with the print image divided ontoa plurality of pages of recording paper. That is, in the configurationdisclosed in Patent Document 3, because the relationship of themulti-feeding state with the structure of the mechanism of the imageforming portion and the feed method is not considered at all, the sortof problem described above occurs.

DISCLOSURE OF INVENTION

The present invention was made in consideration of the problemsdescribed above, and it is an object thereof to provide an imageprocessing apparatus, image forming apparatus, electronic equipment, andimage forming method in which, in the case that multi-feeding ofrecording paper has occurred, by considering the structure of themechanism of the image forming portion, feed method, and the like, it ispossible to appropriately execute continuation and prohibition of imageformation in response to the multi-fed state.

An image processing apparatus according to the present inventionincludes a paper transport system that transports paper and an imageprocessing system that performs image forming processing for papertransported by the paper transport system, and when, in the case thatmulti-feeding has occurred in which when a first paper is transported bythe paper transport system another paper is also transported, and theother paper is not positioned between the first paper and a workingportion of the image processing system, the working portion of the imageprocessing system is allowed to operate.

Alternatively, an image forming apparatus according to the presentinvention includes a recording paper transport system that transportsrecording paper and an image forming system that forms an image onrecording paper transported by the recording paper transport system, andwhen, in the case that multi-feeding has occurred in which when a firstrecording paper is transported by the recording paper transport systemanother recording paper is also transported, and the other recordingpaper is not positioned between the first recording paper and an imageforming portion of the image forming system, image forming processingfor the first recording paper by the image forming system is continued.

Alternatively, an image forming apparatus according to the presentinvention includes a movable feed member that supplies recording paperby making contact with recording paper that has been placed on aplacement stage and extracting that recording paper from the placementstage with frictional force between the feed member and the contactedrecording paper, and an image forming system that forms an image on therecording paper supplied by the feed member, and when, in the case thatmulti-feeding has occurred in which when a first recording paper istransported by the feed member another recording paper is also supplied,and the contact face of the first recording paper contacted by the feedmember is the image forming face, image forming processing for the firstrecording paper by the image forming system is continued. Also, an imageforming apparatus according to the present invention includes a movablefeed member that supplies recording paper by making contact withrecording paper that has been placed on a placement stage and extractingthat recording paper from the placement stage with frictional forcebetween the feed member and the contacted recording paper, and an imageforming system that forms an image on the recording paper supplied bythe feed member, and when, in the case that multi-feeding has occurredin which when a first recording paper is transported by the feed memberanother recording paper is also supplied, and the contact face of thefirst recording paper contacted by the feed member is not the imageforming face, image forming processing for the other recording paper bythe image forming system is continued.

According to an image forming apparatus having this sort ofconfiguration, the operation of the apparatus is not stopped even in thecase that recording paper, which is paper, has been multi-fed, and so itis possible to improve job efficiency. Also, when operation of theapparatus is stopped due to multi-feeding, recording paper accumulatesin the apparatus and wasteful work such as the removal of recordingpaper (jam processing) is generated for the operator, but it is possibleto decrease this sort of wasteful work. Further, it is possible toprevent damage to a photosensitive drum or transfer apparatus by jamprocessing, and pollution inside the apparatus such as unfixed toner canbe prevented.

Alternatively, an image forming apparatus according to the presentinvention includes a recording paper transport system that transportsrecording paper and an image forming system that forms an image onrecording paper transported by the recording paper transport system, andwhen, in the case that multi-feeding has occurred in which when a firstrecording paper is transported by the recording paper transport systemanother recording paper is also transported, and the other recordingpaper is positioned between the first recording paper and an imageforming portion of the image forming system, image forming processingfor the first recording paper by the image forming system is prohibited.

Alternatively, an image forming apparatus according to the presentinvention includes a movable feed member that supplies recording paperby making contact with recording paper that has been placed on aplacement stage and extracting that recording paper from the placementstage with frictional force between the feed member and the contactedrecording paper, and an image forming system that forms an image on therecording paper supplied by the feed member, and when, in the case thatmulti-feeding has occurred in which when a first recording paper istransported by the feed member another recording paper is also supplied,the contact face of the first recording paper contacted by the feedmember is not the image forming face, image forming processing for thefirst recording paper by the image forming system is prohibited.

According to an image forming apparatus having this sort ofconfiguration, in the case that the other recording paper is positionedbetween the first recording paper and the image forming portion of theimage forming system, that is, when the contact face of the firstrecording paper contacted by the feed member is not the image formingface, and image formation is continued, the image is divided and alsoformed on the multi-fed recording paper, and a good image can not beobtained, but by prohibiting image formation it is possible to decreasewasteful consumption of feed.

A configuration may also be adopted in which, in the image formingapparatus of the present invention, a detector that detectsmulti-feeding of the first recording paper and the other recording paperis provided between the placement stage of the recording paper and theimage forming portion of the image forming system. In this case, thedetector detects multi-feeding by detecting an edge portion of themulti-fed other recording paper.

According to an image forming apparatus having this sort ofconfiguration, it is possible to detect multi-feeding of the recordingpaper before it arrives at the image forming portion, and so it becomespossible to judge whether or not image formation will be continuouslyperformed, and to perform control suited to the multi-fed state whenimage formation is performed in the multi-fed state, and so a good imageis obtained when image formation has been performed.

A configuration may also be adopted in which, in the image formingapparatus of the present invention, a transfer bias is increased fromthe normal transfer bias when performing image formation in the casethat multi-feeding has occurred. Thus, toner on a photosensitive drum,which is the image forming portion, is stably transferred to therecording paper even for a halftone image or the like, and so stableimage formation can be performed and it is possible to obtain a goodimage.

A configuration may also be adopted in which, in the image formingapparatus of the present invention, a fixing temperature is increasedfrom the normal fixing temperature when performing image formation inthe case that multi-feeding has occurred. Thus stable fixing is possiblein a fixer.

A configuration may also be adopted in which, in the image formingapparatus of the present invention, a trailing edge detector is providedthat detects the trailing edge of the recording paper, and when imageformation is performed in the case that multi-feeding has occurred, thedetection information of the trailing edge of the recording paper fromthe trailing edge detector is treated as void. A configuration may alsobe adopted in which, in the image forming apparatus of the presentinvention, when image formation is performed in the case thatmulti-feeding has occurred, a reference for judging the occurrence ofdefects based on the detection information of the trailing edge of therecording paper from the trailing edge detector is changed to areference taking into consideration the extent of multi-feeding.

According to an image forming apparatus having this sort ofconfiguration, in the case that image formation is performed formulti-fed recording paper, it is possible to prevent erroneous detectionrelated to recording paper transport. That is, when there ismulti-feeding, because the length of the transported recording paperincreases to the extent of multi-feeding, although the timing ofdetection of the trailing edge of the recording paper by the trailingedge detector is delayed to that extent and erroneous detection ispossible, in the present invention, by either treating the trailing edgedetection information as void or adopting a judgment reference that hastaken the extent of multi-feeding into consideration in the case ofmulti-feeding, it is possible to reliably prevent this sort of erroneousdetection.

A configuration may also be adopted in which, in the image formingapparatus of the present invention, a notifier is provided that, in thecase that multi-feeding has been detected by the detector, makes such anotification. In this case, the notifier makes a notification ofinformation of the recording paper for which image formation could notbe performed due to multi-feeding. In this way, by notifying theoperator of information of the recording paper for which image formationcould not be performed due to multi-feeding (for example, what pagenumber from the beginning, or what page number), it is possible toclearly indicate to the user the presence of recording paper for whichimage formation could not be performed.

Alternatively, an image forming method according to the presentinvention includes a step of transporting recording paper page by pagewith a recording paper transport system, a step of detectingmulti-feeding by detecting another recording paper when transporting afirst recording paper, and a step of continuing an image formingoperation for the first recording paper by the image forming system inthe case that the other recording paper is not positioned between thefirst recording paper and the image forming portion of the image formingsystem, even in the case that multi-feeding has been detected.

Alternatively, an image forming method according to the presentinvention includes a step of transporting recording paper page by pagewith a recording paper transport system, a step of detectingmulti-feeding by detecting another recording paper when transporting afirst recording paper, and a step of continuing an image formingoperation for the other recording paper by the image forming system inthe case that multi-feeding has been detected and the other recordingpaper is positioned between the first recording paper and the imageforming portion of the image forming system.

According to an image forming method having this sort of configuration,the operation of the apparatus is not stopped even in the case that therecording paper, which is paper, has been multi-fed, and so it ispossible to improve job efficiency. Also, when operation of theapparatus is stopped due to multi-feeding, recording paper accumulatesin the apparatus and wasteful work such as the removal of recordingpaper (jam processing) is generated for the operator, but it is possibleto decrease this sort of wasteful work. Further, it is possible toprevent damage to the photosensitive drum or transfer apparatus by jamprocessing, and pollution inside the apparatus such as unfixed toner canbe prevented.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view that shows the internal configuration of amultifunction machine as the image forming apparatus of the presentinvention.

FIG. 2 is a functional block diagram that shows the basic configurationof a control system of a multifunction machine of the presentembodiment.

FIG. 3 is schematic view that shows a state in which, in a process oftransporting recording paper housed in a paper cassette to aphotosensitive drum of an image forming portion by transporting therecording paper through a transport path having a straight pathconfiguration, recording paper is multi-fed.

FIG. 4 is a schematic view that shows a state in which, in a process oftransporting recording paper housed in a paper cassette to aphotosensitive drum of an image forming portion by transporting therecording paper through a U-shaped reverse transport path, recordingpaper is multi-fed.

FIG. 5 is a schematic view that shows a state in which, in a process oftransporting recording paper placed in a manual tray to a photosensitivedrum of an image forming portion by transporting the recording paperthrough a U-shaped reverse transport path, recording paper is multi-fed.

FIG. 6 is an explanatory diagram that shows a state in which recordingpaper has been multi-fed when recording paper housed in a paper cassetteis supplied by a pickup roller.

FIG. 7(a) is an explanatory diagram that shows a state in which an imagehas been formed on recording paper that has been multi-fed.

FIG. 7(b) is an explanatory diagram that shows another state in which animage has been formed on recording paper that has been multi-fed.

FIG. 8 is an outline flowchart of an image forming operation whenmulti-feeding occurs in Example 1.

FIG. 9 is an outline flowchart of an image forming operation whenmulti-feeding occurs in Example 2.

FIG. 10 is an outline flowchart of an image forming operation whenmulti-feeding occurs in Example 3.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described by way ofillustrative embodiments with reference to the drawings.

In the present embodiment, a case is described in which the imageforming apparatus of the present invention is applied in a multifunctionmachine.

—Description of the Overall Configuration of the Multifunction Machine—

FIG. 1 shows an overview of the internal configuration of amultifunction machine 1 as an image forming apparatus according to thepresent embodiment. The multifunction machine 1 includes a copier mode,printer mode, and fax mode as image forming modes in which an image isformed on recording paper (including recording media for overheadprojectors and the like), and the modes are selected by a user.

This multifunction machine 1 is provided with a scanner portion 2 as anoriginal reading portion, image forming portion 3, and an automaticoriginal feed portion 4. Following is a description of each portion.

<Description of the Scanner Portion 2>

The Scanner Portion 2 reads an image of an original that has been placedon an original stage 41 made from transparent glass or the like, or animage of originals supplied page by page by the automatic original feedportion 4, and creates image data. This scanner portion 2 includes anexposing light source 21, a plurality of reflecting mirrors 22, 23, and24, an imaging lens 25, and a photoelectric transducer (CCD: ChargeCoupled Device) 26.

The exposing light source 21 irradiates light to an original that hasbeen placed on the original stage 41 of the automatic original feedportion 4 or an original that is transported through the automaticoriginal feed portion 4. In the manner of an optical path 20 shown inFIG. 1, the reflecting mirrors 22, 23, and 24 reflect reflected lightfrom the original in the leftward direction in the diagram, then reflectthat light downward, then reflect that light in the rightward directionin the diagram towards the imaging lens 25.

As an original image reading operation, when an original has been placedon the original stage 41 (when used as a “stationary sheet system”), theexposing light source 21 and the reflecting mirrors 22, 23, and 24 scanin the horizontal direction along the original stage 41, and read animage of the entire original. On the other hand, when reading anoriginal that is transported through the automatic original feed portion4 (when used as a “moving sheet system”), the exposing light source 21and the reflecting mirrors 22, 23, and 24 are fixed in the positionshown in FIG. 1, and when the original passes an original readingportion 42 of the automatic original feed portion 4 described below, animage of that original is read.

Light that has been reflected by the reflecting mirrors 22, 23, and 24and has passed the imaging lens 25 is guided to the photoelectrictransducer 26, and in this photoelectric transducer 26 the reflectedlight is converted to an electrical signal (original image data).

<Description of the Image Forming Portion 3>

The image forming portion 3 includes an image forming system 31 and apaper transport system 32.

The image forming system 31 includes a laser scanning unit (LSU) 31 aand a photosensitive drum 31 b as a drum-type image carrier. The laserscanning unit 31 a irradiates the surface of the photosensitive drum 31b with laser light based on the original image data that has beenconverted in the photoelectric transducer 26. The photosensitive drum 31b rotates in the direction indicated by the arrow in FIG. 1, and bylaser light being irradiated from the laser scanning unit 31 a, anelectrostatic latent image is formed on the surface of thephotosensitive drum 31 b.

Other than the laser scanning unit 31 a, a development apparatus(development mechanism) 31 c, a transfer unit (transfer mechanism) 31 d,a cleaning apparatus (cleaning mechanism) 31 e, an unshown chargeremoval unit, and a charging unit 31 f are disposed in order in thecircumferential direction around the outer circumference of thephotosensitive drum 31 b. The development apparatus 31 c develops theelectrostatic latent image that has been formed on the surface of thephotosensitive drum 31 b into a visible image with toner (manifestingagent). The transfer unit 31 d transfers the toner image that has beenformed on the surface of the photosensitive drum 31 b to recording paperas a recording medium. The cleaning apparatus 31 e removes tonerremaining on the surface of the photosensitive drum 31 b after tonertransfer. The charge removal unit removes an electrical charge remainingon the surface of the photosensitive drum 31 b. The charging unit 31 fcharges the surface of the photosensitive drum 31 b to a predeterminedpotential before an electrostatic latent image is formed.

Thus, when forming an image on recording paper, the surface of thephotosensitive drum 31 b is charged to a predetermined potential by thecharging unit 31 f, and the laser scanning unit 31 a irradiates laserlight based on the original image data to the surface of thephotosensitive drum 31 b. Afterwards, the development apparatus 31 cdevelops a visible image on the surface of the photosensitive drum 31 bwith toner, and a toner image is transferred to the recording paper bythe transfer unit 31 d. Afterwards, the toner remaining on the surfaceof the photosensitive drum 31 b is removed by the cleaning apparatus 31e, and the electrical charge remaining on the surface of thephotosensitive drum 31 b is removed by the charge removal unit. By doingso, one cycle of the operation that forms an image on the recordingpaper (print operation) is concluded. By repeating this cycle, it ispossible to successively form images on a plurality of pages ofrecording paper.

On the other hand, the paper transport system 32 allows image formationby the image forming system 31 to be performed by transporting recordingpaper housed in the paper cassette 33 as a paper housing portion orrecording paper placed in the manual tray 34 page by page, anddischarges recording paper for which image formation has been performedto a discharge tray 35 as a paper discharge portion.

This paper transport system 32 includes a main transport path 36 and areverse transport path 37. One end of the main transport path 36 isbranched into two, with one branch end facing the discharge side of thepaper cassette 33 and the other branch end facing the discharge side ofthe manual tray 34. The other end of the main transport path 36 facesthe discharge tray 35. One end of the reverse transport path 37 isconnected to the main transport path 36 on the side upstream (below, inthe figure) from the position where the transfer unit 31 d is disposed,and the other end is connected to the main transport path 36 on the sidedownstream (above, in the figure) from the position where the transferunit 31 d is disposed.

A pickup roller 36 a with a semicircular-shaped cross section isdisposed at one branch end (the portion facing the discharge end of thepaper cassette 33) of the main transport path 36. When this pickuproller 36 a rotates, it makes contact with the topmost recording paperhoused in the paper cassette 33. When doing so, the movement of thepickup roller 36 a is transmitted to that recording paper by thefrictional force between the pickup roller 36 a and the recording paperwith which it is in contact, and that recording paper is extracted fromthe paper cassette 33. In this manner, it is possible to intermittentlyfeed the recording paper housed in the paper cassette 33 page by page tothe main transport path 36. Likewise, a pickup roller 36 b with asemicircular-shaped cross section is disposed at the other branch end(the portion facing the discharge end of the manual tray 34) of the maintransport path 36. Due to rotation of this pickup roller 36 b, it ispossible to intermittently feed the recording paper placed in the manualtray 34 page by page to the main transport path 36.

Registration rollers 36 d are disposed on the side upstream from theposition where the transfer unit 31 d is disposed in this main transportpath 36. These registration rollers 36 d transport recording paper whilematching the positions of the recording paper and the toner image on thesurface of the photosensitive drum 31 b.

On the side further upstream than the position at which the registrationrollers 36 d are disposed and downstream from the branch portion of themain transport path 36, a paper detector 36 c is disposed that detectsan edge portion of the transported recording paper. The paper detector36 c serves as a multi-feeding detector that detects multi-feeding ofthe recording paper, described below, and as a trailing edge detectorthat detects the trailing edge of the recording paper.

On the downstream side of the position at which the transfer unit 31 dis disposed in the main transport path 36, a fixing apparatus 39 isdisposed that is provided with a pair of fixing rollers 39 a and 39 bfor fixing the toner image transferred to the recording paper with heat.Further, at the downstream end of the main transport path 36, dischargerollers 36 e are disposed for discharging the recording paper to thedischarge tray 35.

A branch catch 38 is disposed at the position connecting the upstreamend of the reverse transport path 37 to the main transport path 36. Thisbranch catch 38 is rotatable around a horizontal axis between a firstposition shown by a solid line in FIG. 1 and a second position thatopens the reverse transport path 37 by rotating from the first positionin the counterclockwise direction in the figure. When this branch catch38 is in the first position, the recording paper is transported towardthe discharge tray 35, and when the branch catch 38 is in the secondposition, the recording paper can be supplied to the reverse transportpath 37. Transport rollers 37 a are disposed in the reverse transportpath 37, and in the case that the recording paper has been supplied tothe reverse transport path 37 (in the case that the recording paper hasbeen supplied to the reverse transport path 37 by so-called switchbacktransport), the recording paper is transported by these transportrollers 37 a, and again transported through the main transport path 36toward the transfer unit 31 d by being reversed on the upstream side ofthe registration rollers 36 d. That is, it becomes possible to form animage on the rear face of the recording paper.

In the image forming portion 3 with the above configuration, the papercassette 33, the manual tray 34, the pickup rollers 36 a and 36 b, thepaper detector 36 c, and the registration rollers 36 d are together alsoreferred to hereinafter as a recording paper feed portion.

<Description of the Automatic Original Feed Portion 4>

Following is a description of the automatic original feed portion 4.This automatic original feed portion 4 is configured as a so-calledautomatic duplex original transport apparatus. This automatic originalfeed portion 4 can be used as a moving sheet system, and includes anoriginal tray 43 as an original placement portion, a middle tray 44, anoriginal discharge tray 45 as an original discharge portion, and anoriginal transport system 46 that transports an original between thetrays 43, 44, and 45.

The original transport system 46 is provided with a main transport path47 for transporting an original that has been placed on the originaltray 43 to the middle tray 44 or the original discharge tray 45 via anoriginal reading portion 42, and a sub transport path 48 for feeding anoriginal on the middle tray 44 to the main transport path 47.

An original pickup roller 47 a and a separation roller 47 b are disposedat the upstream end (the portion facing the discharge side of theoriginal tray 43) of the main transport path 47. A separation plate 47 cis disposed on the bottom side of the separation roller 47 b, and onepage of the originals on the original tray 43 is supplied to the maintransport path 47 by passing between this separation roller 47 b and theseparation plate 47 c along with rotation of the original pickup roller47 a. PS rollers 47 e are disposed on the downstream side of a linkingportion 49 of the main transport path 47 and the sub transport path 48.These PS rollers 47 e adjust the leading edge of the original and theimage reading timing of the scanner portion 2 and feed the original tothe original reading portion 42. That is, these PS rollers 47 etemporarily stop transport of the original with the original in asupplied state, adjust the above timing, and feed the original to theoriginal reading portion 42.

The original reading portion 42 is provided with a glass platen 42 a andan original pressing plate 42 b, and when the original supplied from thePS rollers 47 e passes between the glass platen 42 a and the originalpressing plate 42 b, light from the exposing light source 21 passesthrough the glass platen 42 a and is irradiated onto the original. Atthis time, the acquisition of original image data by the scanner portion2 is performed. Biasing force is conferred on the back face (top face)of the original pressing plate 42 b by a coil spring not shown in thefigure. Thus, the original pressing plate 42 b is in contact with theglass platen 42 a with a predetermined pressure, and when the originalpasses the original reading portion 42, the original is prevented fromrising up from the glass platen 42 a.

Transport rollers 47 f and original discharge rollers 47 g are providedon the downstream side of the glass platen 42 a. A configuration isadopted in which an original that has passed the glass platen 42 a isdischarged to the middle tray 44 or the original discharge tray 45 viathe transport rollers 47 f and the original discharge rollers 47 g.

A middle tray swing plate 44 a is disposed between the originaldischarge rollers 47 g and the middle tray 44. This middle tray swingplate 44 a swings centered on the edge portion of the middle tray 44side, and can swing between a normal position shown by a solid line inthe figure and a flipped up position flipped upward from the normalposition. When the middle tray swing plate 44 a is in the flipped upposition, an original that has been discharged from the originaldischarge rollers 47 g is recovered to the original discharge tray 45.On the other hand, when the middle tray swing plate 44 a is in thenormal position, an original that has been discharged from the originaldischarge rollers 47 g is discharged to the middle tray 44. Whendischarging to this middle tray 44, the marginal edge of the original isin a state sandwiched between the original discharge rollers 47 g, theoriginal is supplied to the sub transport path 48 by the reverserotation of the original discharge rollers 47 g from this state, and theoriginal is again fed out to the main transport path 47 via this subtransport path 48. This reverse rotation operation of the originaldischarge rollers 47 g is performed after adjusting the timing forfeeding out the original to the main transport path 47 and the imagereading. Thus, an image of the rear face of the original is read by theoriginal reading portion 42.

—Description of the Basic Operation of the Multifunction Machine—

As the operation of the multifunction machine 1 configured in the mannerdescribed above, first, when the multifunction machine 1 functions as aprinter (printer mode), it receives print data (image data or text data)that has been transmitted from a host apparatus such as a personalcomputer, and temporarily stores this received print data in a buffer(memory) not shown in the figure. Along with storing the print data inthis buffer, the print data is sequentially read from the buffer, andbased on this read print data, an image is formed on recording paper bythe image forming operation of the image forming portion 3 describedabove.

Also, when the multifunction machine 1 functions as a scanner (faxmode), scan image data of an original that has been read by the scannerportion 2 is temporarily stored in the buffer. Along with storing thescan image data in this buffer, the scan image data is sequentiallytransmitted to a host apparatus from the buffer, and an image isdisplayed on a display or the like of this host apparatus.

Further, when the multifunction machine 1 functions as a copy machine(copier mode), an image is formed on recording paper by the imageforming operation of the image forming portion 3 based on the originalimage data that has been read by the scanner function.

Following is a description of the copier mode in more detail.

—Description of the Image Forming Operation in the Copier Mode—

When copying the image of an original to recording paper in the copiermode, after placing the original wished to be copied on the originalstage 41 of the scanner portion 2 or in the original tray 43, settingsare input for the number of pages to print, the print magnification, andthe like by depressing input keys provided in an operating panel portionnot shown in the figure, and the copy operation is started by depressinga start key not shown in the figure.

When the start key is pressed, in the multifunction machine 1, thepickup roller 36 a or 36 b rotates and recording paper is supplied tothe main transport path 36 from the paper cassette 33 or the manual tray34. The supplied recording paper is transported to the registrationrollers 36 d provided on the main transport path 36. The leading edgeportion in the transport direction of the recording paper that has beentransported to the registration rollers 36 d is chucked by theregistration rollers 36 d such that the sub scanning direction of therecording paper and the axial direction of the registration rollers 36 dare parallel, in order to match its position to the position of thetoner image formed on the photosensitive drum 31 b that should betransferred to the paper.

After image processing has been performed with conditions that have beeninput using input keys or the like, the image data read by the scannerportion 2 is transmitted to the laser scanning unit 31 a as print data.The laser scanning unit 31 a forms an electrostatic latent image on thesurface of the photosensitive drum 31 b, which has been charged to apredetermined potential by the charger 31 f, by irradiating laser lightbased on the image data via a polygon mirror and various lenses notshown in the figure.

Afterwards, toner affixed to the surface of an MG roller 31 c 1 thatfaces the photosensitive drum 31 b provided in an unshown developer tankof the development apparatus 31 c is attracted to and affixes to thesurface of the photosensitive drum 31 b according to the potential gapon the surface of the photosensitive drum 31 b, so that an electrostaticlatent image is made as a development. The toner remaining on thephotosensitive drum 31 b is scraped off by a cleaning blade of a drumunit not shown in the figure, and recovered by a cleaner unit not shownin the figure.

Next, the positions of the recording paper chucked by the registrationrollers 36 d and the toner image formed on the surface of thephotosensitive drum 31 b are matched (timing is adjusted) by theregistration rollers 36 d, and the recording paper is transportedbetween the photosensitive drum 31 b and the transfer unit 31 d. Then,the toner image on the surface of the photosensitive drum 31 b istransferred to the recording paper using an unshown transfer rollerprovided in the transfer unit 31 d.

Heat and pressure are added to the recording paper for which transfer ofthe toner image is completed due to the recording paper passing betweenthe fixing rollers 39 a and 39 b of the fixing apparatus 39, the tonerimage is fused and firmly fixed, and the recording paper is dischargedto the discharge tray 35 by the discharge rollers 36 e.

—Block Configuration of the Control System—

FIG. 2 is a functional block diagram that shows the basic configurationof the control system of the multifunction machine 1.

A main CPU 101 is provided in the multifunction machine 1 for performingintegrated control of the included devices (the scanner portion 2, theimage forming portion 3, and the automatic original feed portion 4), andbi-directionally connected to this main CPU 101 are an original feedcontrol portion 102 that controls automatic feed of an original, acharging control portion 103 that controls each portion of the imageforming portion 3, a development control portion 104, a transfer controlportion 105, a fixing control portion 106, and a paper transport controlportion 107 provided with the paper detector 36 c that detects an edgeportion of the paper. Also connected to the main CPU 101 is an operatingcontrol portion 108 that outputs a signal from an operating panelportion not shown in the figure with which an operator performs an inputoperation, and that allows a display operation to be performed on theoperating panel portion according to the signal from the main CPU 101.

—Description of the State of the Recording Paper when Multi-FeedingOccurs in the Recording Paper Feed Portion—

FIG. 3 is a schematic view that shows how recording paper housed in thepaper cassette 33 is transported to the photosensitive drum 31 b of theimage forming portion 3 in the multifunction machine 1 having theabove-described configuration.

When recording paper P has been supplied successively from the upperportion of the paper cassette 33 by the pickup roller 36 a, because themain transport path 36 is configured with a straight path, even in thecase that multi-feeding has occurred when feeding recording paper,because a multi-fed recording paper P2 is positioned on the bottom sideof a recording paper P1 for which recording should be performed, and arecording face (image forming face) P1 a of the recording paper P1 forwhich recording should be performed faces the photosensitive drum 31 b,it is possible to form an image on the recording paper P1.

FIG. 4 schematically shows a case in which the configuration is somewhatdifferent from the multifunction machine 1 with the configurationdescribed above. The main transport path 36 from the paper cassette 33to the photosensitive drum 31 b is not formed in a straight path, but aU-shaped reverse transport path 36A.

In this configuration, when recording paper P has been suppliedsuccessively from the upper portion of the paper cassette 33 by thepickup roller 36 a, because the main transport path is configured by theU-shaped reverse transport path 36A, in the case that multi-feeding hasoccurred when feeding recording paper, due to vertical reversal themulti-fed recording paper P2 is positioned on the top side of therecording paper P1 for which recording should be performed, and themulti-fed recording paper P2 is positioned between the recording face(image forming face) P1 a of the recording paper P1 for which recordingshould be performed and the photosensitive drum 31 b. Accordingly, inthis case it is not possible to perform good image formation on therecording paper P1.

FIG. 5 shows how recording paper P placed on the manual tray 34 istransported to the photosensitive drum 31 b, and like FIG. 4, shows astructure in which reverse transport is performed by a U-shaped reversetransport path 36A2.

Accordingly, in this case as well, as in the case of reverse feed shownin FIG. 4, when multi-feeding has occurred, due to vertical reversal themulti-fed recording paper P2 is positioned on the top side of therecording paper P1 for which recording should be performed, and themulti-fed recording paper P2 is positioned between the recording face(image forming face) P1 a of the recording paper P1 for which recordingshould be performed and the photosensitive drum 31 b. Accordingly, inthis case as well it is not possible to perform good image formation onthe recording paper P1.

FIG. 6 shows a state in which recording paper has been multi-fed whenrecording paper P stored in the paper cassette 33 is supplied by apickup roller 36 a. FIG. 7(a) shows a state in which an image has beenformed on recording paper that has been multi-fed. FIG. 7(b) showsanother state in which an image has been formed on recording paper thathas been multi-fed.

FIG. 7(a) shows an instance in which top-intake and straight transporthave been performed (the instance shown in FIG. 3), for example, andbecause the recording paper P2 that has been multi-fed is positionedbelow the recording paper P1 for which recording should be performed(the side opposite to the image forming portion), recording can beperformed on the recording paper P1 for which recording should beperformed. Also, because position matching of a leading edge portion P11of the recording paper P1 is performed by the registration rollers 36 dprovided on the downstream side of the photosensitive drum 31 b, goodimage formation can be performed for the recording paper P1.

FIG. 7(b) shows an instance in which top-intake and reverse feed havebeen performed (the instance shown in FIGS. 4 and 5), for example, andbecause the recording paper P2 that has been multi-fed is positionedabove the recording paper P1 for which recording should be performed(the side of the image forming portion), an image is mainly formed onthe second page of recording paper P2 that has been multi-fed. In thiscase, matching of the leading edge of the recording paper is performedby the registration rollers 36 d provided on the downstream side of thephotosensitive drum 31 b, but because the leading edge adjustment at theregistration rollers 36 d is performed at the leading edge portion P11of the recording paper P1 for which recording should be performed, animage is formed across the first page of recording paper P1 and thesecond page of recording paper P2 as shown in the figure, leading towasteful consumption of recording paper, toner, ink, and the like.

Following is a description of examples of an image forming operationwhen multi-feeding occurs in the image forming portion 3, with referenceto the state of the recording paper when multi-feeding has occurred inthe recording paper feed portion described above.

EXAMPLE 1

Example 1 is an example of an image forming operation when multi-feedingoccurs according to the main transport path 36 with a straight pathconfiguration shown in FIG. 3.

That is, in the image forming portion 3 provided with the main transportpath 36 having a straight path configuration, even when multi-feeding isdetected, as shown in FIG. 3, the multi-fed recording paper P2 is notpositioned between the recording paper P1 for which recording should beperformed and the photosensitive drum 31 b, and so in this case theoperation that forms an image on the recording paper P1 continues asusual. In this case, the multi-fed recording paper P2 is only passedwith the recording paper P1, and afterward the recording paper P2 isreused.

Next is a description of multi-feeding detection.

In the present embodiment, a new detection portion only for detectingmulti-feeding is not provided; a paper detector 36 c for detecting jamsand the like is also used for detecting multi-feeding by detecting theleading edge portion and the trailing edge portion of the recordingpaper. This paper detector 36 c is configured by a reflecting-type photocoupler, for example, and detects multi-feeding by detecting a shadow orthe like of an edge portion of multi-fed recording paper after detectingthe leading edge portion of the recording paper and before detecting thetrailing edge portion. The inventors of the present invention haveconfirmed through testing and the like that multi-feeding of therecording paper can be reliably detected even when the paper detector 36c is also used as the multi-feeding detection portion.

In Example 1, as shown in FIG. 3, in the case that the paper detector 36c is positioned on the top side of the main transport path 36 having astraight path configuration (shown by a solid line in the figure),multi-feeding is detected by detecting a trailing edge portion P12 ofthe recording paper P1 for which recording should be performed. On theother hand, in the case that the paper detector 36 c is positioned onthe bottom side of the main transport path 36 having a straight pathconfiguration (shown by an imaginary line in the figure), multi-feedingis detected by detecting a leading edge portion P21 of the multi-fedrecording paper P2.

Also, because the paper detector 36 c for detecting multi-feeding isdisposed on the upstream side of the photosensitive drum 31 b, it ispossible to detect multi-feeding of the recording paper before itarrives at the photosensitive drum 31 b. Accordingly, it is possible tojudge whether or not image formation will continue as-is before an imageis actually formed on the recording paper, and when continuing as-is, byperforming control suitable for the multi-fed state, it is possible toobtain a good image even in the case that an image has been formed. Thissort of judgment and control is executed by the paper transport controlportion 107 shown in FIG. 2 based on the results of detection by thepaper detector 36 c.

FIG. 8 is an overall flowchart of the image forming operation whenmulti-feeding occurs in Example 1. Here, a configuration is adopted iswhich the paper detector 36 c is positioned on the bottom side of themain transport path 36 (shown by an imaginary line in FIG. 3).Accordingly, by detecting the leading edge portion P21 of the multi-fedrecording paper P2, it is possible to detect multi-feeding beforestarting to form an image on the recording paper P1 for which recordingshould be performed.

As shown in FIG. 8, first, paper detection is performed by the paperdetector 36 c (Step S201). Then, it is judged whether or not the leadingedge portion P21 of the multi-fed recording paper P2 has also beendetected in succession to the recording paper P1 for which recordingshould be performed (Step S202). If it has been detected, then theoperation advances to Step S203, and if it has not been detected, thenthe operation advances to Step S204.

In the case that multi-feeding has been detected, the occurrence ofmulti-feeding is stored (Step S203), and the operation advances to StepS204 in order to continue the image forming operation as-is on therecording paper P1 for which recording should be performed.

Then, formation of an image on the recording paper P1 for whichrecording should be performed is started (Step S204), afterward it isjudged whether or not image formation has finished (Step S205), and thisjudgment is repeated until image formation is finished.

EXAMPLE 2

Example 2 is an example of the image forming operation whenmulti-feeding occurs according to the U-shaped reverse transport path36A shown in FIG. 4 and the U-shaped reverse transport path 36A2 shownin FIG. 5.

That is, when adopting a configuration in which the image formingportion 3 is provided with the U-shaped reverse transport path 36A orthe U-shaped reverse transport path 36A2 instead of the main transportpath 36 having a straight path configuration, in the case thatmulti-feeding has been detected, when the multi-fed recording paper P2and the recording paper P1 for which recording should be performed makecontact with the photosensitive drum 31 b as shown in FIGS. 4 and 5, therecording face (image forming face) P1 a of the recording paper P1 forwhich recording should be performed is stacked below the multi-fedrecording paper P2. That is, the multi-fed recording paper P2 becomes anobstacle between the recording face (image forming face) P1 a of therecording paper P1 for which recording should be performed and thephotosensitive drum 31 b. Accordingly, in that case the operation thatforms an image on the recording paper P1 is stopped.

In Example 2, in the case that recording paper is supplied from thepaper cassette 33 shown in FIG. 4 and the paper detector 36 c ispositioned on the left side of the reverse transport path 36A (shown bya solid line in FIG. 4), multi-feeding is detected by detecting thetrailing edge portion P12 of the recording paper P1. On the other hand,in the case that the paper detector 36 c is positioned on the right sideof the reverse transport path 36A (shown by an imaginary line in FIG.4), multi-feeding is detected by detecting the leading edge portion P21of the multi-fed recording paper P2.

In the case that recording paper is supplied from the manual tray 34shown in FIG. 5 and the paper detector 36 c is positioned on the leftside of the reverse transport path 36A2 (shown by a solid line in FIG.5), multi-feeding is detected by detecting the leading edge portion P21of the multi-fed recording paper P2. On the other hand, in the case thatthe paper detector 36 c is positioned on the right side of the reversetransport path 36A2 (shown by an imaginary line in FIG. 5),multi-feeding is detected by detecting the trailing edge portion P12 ofthe recording paper P1.

FIG. 9 is an overall flowchart of the image forming operation whenmulti-feeding occurs in Example 2. Here, a configuration is adopted inwhich the paper detector 36 c is positioned on the right side of thereverse transport path 36A (shown by an imaginary line in FIG. 4).Accordingly, by detecting the leading edge portion P21 of the multi-fedrecording paper P2, it is possible to detect multi-feeding beforestarting to form an image on the recording paper P1 for which recordingshould be performed.

As shown in FIG. 9, first, paper detection is performed by the paperdetector 36 c (Step S301). Then, it is judged whether or not the leadingedge portion P21 of the multi-fed recording paper P2 has also beendetected in succession to the recording paper P1 for which recordingshould be performed (Step S302). If it has been detected, then theoperation advances to Step S303, and if it has not been detected, thenthe operation advances to Step S304.

In the case that multi-feeding has not been detected, formation of animage on the recording paper P1 for which recording should be performedis started (Step S304), afterward it is judged whether or not imageformation has finished (Step S305), and this judgment is repeated untilimage formation is finished.

In the case that multi-feeding has been detected, the occurrence ofmulti-feeding is stored (Step S303), image formation on the recordingpaper P1 for which recording should be performed is suspended and theimage forming operation is finished.

EXAMPLE 3

Example 3 is another example of the image forming operation whenmulti-feeding occurs according to the U-shaped reverse transport path36A shown in FIG. 4 and the U-shaped reverse transport path 36A2 shownin FIG. 5.

That is, when adopting a configuration in which the image formingportion 3 is provided with the U-shaped reverse transport path 36A orthe U-shaped reverse transport path 36A2 instead of the main transportpath 36 having a straight path configuration, in the case thatmulti-feeding has been detected, as shown in FIGS. 4 and 5, themulti-fed recording paper P2 becomes an obstacle between the recordingface (image forming face) P1 a of the recording paper P1 for whichrecording should be performed and the photosensitive drum 31 b.Accordingly, in this case it is not possible to form an image on therecording paper P1. However, it is possible to form an image on themulti-fed recording paper P2. Accordingly, in Example 3, an image is notformed on the recording paper P1 for which recording should beperformed, and the operation forming an image on the multi-fed recordingpaper P2 is continued.

In this case, as shown in FIGS. 4 and 5, it is necessary to delay thetiming of image formation by the amount of a displacement length Da (seeFIG. 4) or Db (FIG. 5) of the stacking of the recording paper P1 and therecording paper P2. Because detection of multi-feeding can be performedby detecting the leading edge portion P21 of the multi-fed recordingpaper P2 at the position where the paper detector 36 c is disposed (theposition shown by an imaginary line in FIG. 4, and the position shown bya solid line in FIG. 5), it is possible to form an image on therecording paper P2 by adjusting the position of the leading edge portionof the multi-fed recording paper P2 based on the timing of thisdetection. This sort of position adjustment control is executed with thepaper transport control portion 107 shown in FIG. 2.

FIG. 10 is an overall flowchart of the image forming operation whenmulti-feeding occurs in Example 3. Here, a configuration is adopted inwhich the paper detector 36 c is positioned on the right side of thereverse transport path 36A (shown by an imaginary line in FIG. 4).Accordingly, by detecting the leading edge portion P21 of the multi-fedrecording paper P2, it is possible to detect multi-feeding beforestarting to form an image on the recording paper P1 for which recordingshould be performed.

As shown in FIG. 10, first, paper detection is performed by the paperdetector 36 c (Step S401). Then, it is judged whether or not the leadingedge portion P21 of the multi-fed recording paper P2 has also beendetected in succession to the recording paper P1 for which recordingshould be performed (Step S402). If it has been detected, then theoperation advances to Step S403, and if it has not been detected, thenthe operation advances to Step S404.

In the case that multi-feeding has not been detected, formation of animage on the recording paper P1 for which recording should be performedis started (Step S404), afterward it is judged whether or not imageformation has finished (Step S405), and this judgment is repeated untilimage formation is finished.

In the case that multi-feeding has been detected, the occurrence ofmulti-feeding is stored (Step S403), and next image formation on themulti-fed recording paper P2 is started (Step S406). At this time, thetiming for starting image formation is delayed according to thedisplacement length Da of the stacking of the recording paper P1 and therecording paper P2. Afterward it is judged whether or not imageformation has finished (Step S407), and this judgment is repeated untilimage formation is finished.

EXAMPLE 4

In Examples 1 and 3, even if multi-feeding has occurred, the imageforming operation continues in a multi-fed state. In this case, thethickness of the paper increases to the extent that the recording paperis multi-fed, and so in the image forming portion 3 it is necessary toperform image formation control that takes this into consideration.

Consequently, in Example 4, in the case that image formation isperformed in a multi-fed state, the transfer bias when forming an imageis elevated above normal (when there is one page of paper) bycontrolling the charging control portion 103 shown in FIG. 2. Thus, thetoner on the photosensitive drum 31 b is stably transferred to therecording paper even for a halftone image or the like, and so stableimage formation can be performed and it is possible to obtain a goodimage.

Also, in Example 4, in the case that image formation is performed in amulti-fed state, the fixing temperature is elevated above normal (whenthere is one page of paper) by controlling the fixing control portion106 shown in FIG. 2. Thus, stable fixing in the fixing apparatus 39becomes possible, and a good image can be obtained.

EXAMPLE 5

In Examples 1 and 3, even if multi-feeding has occurred, the imageforming operation continues in a multi-fed state. In this case, thelength of the recording paper is apparently lengthened to the extentthat the recording paper is multi-fed, and so as a result of theincreased length of the recording paper (that is, the time that passesdue to detection of the leading edge portion and the trailing edgeportion of the recording paper by the paper detector 36 c), this isjudged as the occurrence of a jam by the main CPU 101, and an emergencystop of the image forming operation is performed. Accordingly, in themain CPU 101, it is necessary to perform image formation control thattakes this into consideration.

Consequently, in Example 5, in the case that image formation iscontinued in a multi-fed state even when multi-feeding has occurred, thedetection information of the trailing edge of the recording paper fromthe paper detector 36 c is treated as void. That is, even if the timethat passes due to detection of the leading edge portion and thetrailing edge portion of the recording paper by the paper detector 36 cbecomes longer than a reference time set in an internal portion inadvance that is used for judging a jammed state, this is ignored. Thus,it is possible to continue image formation even in a multi-fed state.

Also, in Example 5, a configuration may be adopted in which, in the casethat image formation is continued in a multi-fed state even whenmulti-feeding has occurred, the reference time set in an internalportion in advance that is used for judging a jammed state is changedlonger to a second reference time by a predetermined length, and jamjudgment is performed as usual. Here, in the case that feed of recordingpaper from the paper cassette 33 or the manual tray 34 is performed in anormal state without multi-feeding, it is necessary to set the secondreference time to a time shorter than the interval from the time thatthe leading edge of the initial recording paper passes the paperdetector 36 c until the time that the leading edge of the next recordingpaper passes the paper detector 36 c. This is because when setting thistime to a longer time, it is possible that a jam will not be able to bedetected even if it actually occurs. In this manner, by changing thereference time to the second reference time, it becomes possible to forman image in a multi-fed state, and a jam can be detected when it occurs.

EXAMPLE 6

In Example 6, a configuration has been adopted in which, in the casethat multi-feeding has been detected in the manner of above Examples 1through 5, an operator is notified that multi-feeding has occurred.

As a notification method, a configuration may be adopted in which anerror message or the like that multi-feeding has occurred is displayedon a display panel provided in an unshown operating panel portion of themultifunction machine 1. It is also possible to notify the operator byemitting a buzzer sound from a built-in buzzer or the like not shown inthe figure, or emitting an electronic sound. It is more effective ifnotification is made with both the display of an error message and anotification sound. Further, a configuration may be adopted in which thecontents displayed on the display panel are not limited to an errormessage; information of recording paper for which image formation hasnot been performed due to multi-feeding is displayed. For example, apage of recording paper for which image formation has not been performeddue to multi-feeding is displayed. Thus, because the operator canclearly understand which page requires reread and image formation to beperformed, the efficiency of reread and image forming processingimproves.

Also, with the present embodiment, a case is described in which an imageforming apparatus was applied to a multifunction machine, but byapplying an image forming apparatus to a scanner apparatus unit, copyapparatus unit, or facsimile apparatus unit, or a multifunction machinein which any two or more of these are combined, it is possible toprovide an electronic equipment in which an improvement in theefficiency of image forming processing has been achieved.

The present invention may be embodied in other forms without departingfrom the spirit or essential characteristics thereof. The embodimentsdisclosed in this application are to be considered in all respects asillustrative and not limiting. The scope of the invention is indicatedby the appended claims rather than by the foregoing description, and allchanges that come within the meaning and range of equivalency of theclaims are intended to be embraced therein.

This application claims priority on Patent Application No. 2003-185361filed in Japan on Jun. 27, 2003, the entire contents of which are herebyincorporated by reference. Patents and publications cited herein arehereby specifically incorporated by reference in their entirety.

INDUSTRIAL APPLICABILITY

In the above manner, the image processing apparatus, image formingapparatus, electronic equipment, and image forming method of the presentinvention are very suitable for, for example, a scanner apparatus, copyapparatus, facsimile apparatus, or a multifunction machine in which twoor more of these are combined.

1. An image processing apparatus comprising a paper transport systemthat transports paper and an image processing system that performs imageforming processing for paper transported by the paper transport system,wherein when, in the case that multi-feeding has occurred in which whena first paper is transported by the paper transport system another paperis also transported, and the other paper is not positioned between thefirst paper and a working portion of the image processing system, theworking portion of the image processing system is allowed to operate. 2.An image forming apparatus comprising a recording paper transport systemthat transports recording paper and an image forming system that formsan image on recording paper transported by the recording paper transportsystem, wherein when, in the case that multi-feeding has occurred inwhich when a first recording paper is transported by the recording papertransport system another recording paper is also transported, and theother recording paper is not positioned between the first recordingpaper and an image forming portion of the image forming system, imageforming processing for the first recording paper by the image formingsystem is continued.
 3. An image forming apparatus provided with amovable feed member that supplies recording paper by making contact withrecording paper that has been placed on a placement stage and extractingthat recording paper from the placement stage with frictional forcebetween the feed member and the contacted recording paper, and an imageforming system that forms an image on the recording paper supplied bythe feed member, wherein when, in the case that multi-feeding hasoccurred in which when a first recording paper is transported by thefeed member another recording paper is also supplied, and the contactface of the first recording paper contacted by the feed member is theimage forming face, image forming processing for the first recordingpaper by the image forming system is continued.
 4. An image formingapparatus provided with a movable feed member that supplies recordingpaper by making contact with recording paper that has been placed on aplacement stage and extracting that recording paper from the placementstage with frictional force between the feed member and the contactedrecording paper, and an image forming system that forms an image on therecording paper supplied by the feed member, wherein when, in the casethat multi-feeding has occurred in which when a first recording paper istransported by the feed member another recording paper is also supplied,and the contact face of the first recording paper contacted by the feedmember is not the image forming face, image forming processing for theother recording paper by the image forming system is continued.
 5. Animage forming apparatus comprising a recording paper transport systemthat transports recording paper and an image forming system that formsan image on recording paper transported by the recording paper transportsystem, wherein when, in the case that multi-feeding has occurred inwhich when a first recording paper is transported by the recording papertransport system another recording paper is also transported, and theother recording paper is positioned between the first recording paperand an image forming portion of the image forming system, image formingprocessing for the first recording paper by the image forming system isprohibited.
 6. An image forming apparatus provided with a movable feedmember that supplies recording paper by making contact with recordingpaper that has been placed on a placement stage and extracting thatrecording paper from the placement stage with frictional force betweenthe feed member and the contacted recording paper, and an image formingsystem that forms an image on the recording paper supplied by the feedmember, wherein when, in the case that multi-feeding has occurred inwhich when a first recording paper is transported by the feed memberanother recording paper is also supplied, and the contact face of thefirst recording paper contacted by the feed member is not the imageforming face, image forming processing for the first recording paper bythe image forming system is prohibited.
 7. The image forming apparatusaccording to claim 3, wherein a detector that detects multi-feeding ofthe first recording paper and the other recording paper is providedbetween the placement stage of the recording paper and the image formingportion of the image forming system.
 8. The image forming apparatusaccording to claim 7, wherein the detector detects multi-feeding bydetecting an edge portion of the multi-fed other recording paper.
 9. Theimage forming apparatus according to claim 2, wherein a transfer bias isincreased from the normal transfer bias when performing image formationin the case that multi-feeding has occurred.
 10. The image formingapparatus according to claim 2, wherein a fixing temperature isincreased from the normal fixing temperature when performing imageformation in the case that multi-feeding has occurred.
 11. The imageforming apparatus according to claim 2, wherein a trailing edge detectoris provided that detects the trailing edge of the recording paper, andwhen image formation is performed in the case that multi-feeding hasoccurred, the detection information of the trailing edge of therecording paper from the trailing edge detector is treated as void. 12.The image forming apparatus according to claim 2, wherein a trailingedge detector is provided that detects the trailing edge of therecording paper, and when image formation is performed in the case thatmulti-feeding has occurred, a reference for judging the occurrence ofdefects based on the detection information of the trailing edge of therecording paper from the trailing edge detector is changed to areference taking into consideration the extent of multi-feeding.
 13. Theimage forming apparatus according to claim 7, wherein a notifier isprovided that, in the case that multi-feeding has been detected by thedetector, makes such a notification.
 14. The image forming apparatusaccording to claim 13, wherein the notifier makes a notification ofinformation of the recording paper for which image formation could notbe performed due to multi-feeding.
 15. An electronic equipment, whereinthe image processing apparatus according to claim 1 is a scannerapparatus, copy apparatus, or facsimile apparatus, or a multifunctionmachine in which any two or more of these are combined.
 16. Anelectronic equipment, wherein the image forming apparatus according toclaim 2 is a scanner apparatus, copy apparatus, or facsimile apparatus,or a multifunction machine in which any two or more of these arecombined.
 17. An image forming method comprising: a step of transportingrecording paper page by page with a recording paper transport system, astep of detecting multi-feeding by detecting another recording paperwhen transporting a first recording paper, and a step of continuing animage forming operation for the first recording paper by the imageforming system in the case that the other recording paper is notpositioned between the first recording paper and the image formingportion of the image forming system, even in the case that multi-feedinghas been detected.
 18. An image forming method comprising: a step oftransporting recording paper page by page with a recording papertransport system, a step of detecting multi-feeding by detecting anotherrecording paper when transporting a first recording paper, and a step ofcontinuing an image forming operation for the other recording paper bythe image forming system in the case that multi-feeding has beendetected and the other recording paper is positioned between the firstrecording paper and the image forming portion of the image formingsystem.